Kate Soper spent much of the fall of 2009 in Cassis, France, on a fellowship from the Camargo Foundation, an institute for the arts and humanities. Soper was in the midst of a doctoral program in composition at Columbia University and had been deeply enmeshed in New York’s thriving, sometimes chaotic new-music scene, but she felt as though she hadn’t yet unlocked something authentic she wanted to achieve in her music. Cassis is a rather remote seaside village, famous for its small coves and dramatic cliffs. Soper spent a lot of time alone in “this huge house with a piano,” she said during a recent phone interview.

“I was sort of able, in silence, to ask myself what I really wanted to do and what I really wanted to say,” she continued. “And I had this urge to communicate something really directly and forcefully, just sort of throw myself into something. I think as a young composer, there’s a lot of insecurity. You end up wanting to hide behind something sturdy — something rigorous or esoteric. And I felt the need to just break through that.”

When she returned to New York, Soper began writing a series of intensely dramatic vocal works, often for herself as singer, which combine raw, theatrical expressivity and unconventional vocal techniques and surfaces. Among these are “Voices From the Killing Jar,” a sequence of eight portraits of women — Clytemnestra, Emma Bovary, Daisy Buchanan — trapped in straitened circumstances. A recording of the piece, for soprano, chamber ensemble, and electronics, was released earlier in the year on Carrier Records. And Soper’s 90-minute opera “Here Be Sirens,” produced by Morningside Opera at New York’s Dixon Place in January, will be revived there for four performances in September.

Those pieces have marked Soper out as a composer of trenchant, sometimes discomfiting, power. Standing behind them is “Helen Enfettered,” a piece for two singers and ensemble that she wrote just prior to her Camargo fellowship, and in which she can now see “all these latent drives that were about to kick me over” in later works. “Helen” will be performed on Sunday at the Tanglewood Contemporary Music Festival, on a program with music by Andrew Waggoner.

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Among the remarkable things about Soper is that composing is only one strand of expression that also includes singing and writing. All three activities go back to her childhood. “When I was young, I would sit at the piano with books of poetry and make stuff up and sing through it,” she said. “It was all total drivel, but I amused myself.”

Tanglewood Festival of Contemporary Music

Those impulses seem to have been similar in intensity, and becoming a composer was less the result of a deep-seated drive than one artistic option among others. When it came time for college, Soper had a strong interest in writing, but since she had “a portfolio of compositions, I thought I would go for that.” She also said that she never had a “Mahler moment” — one of those road-to-Damascus encounters with a specific piece that sets a young composer irrevocably on his or her path.

“That used to make me feel like I had some inadequacy as a composer, because I don’t really derive my deepest influential inspirations from music,” she said. “Something that’s been interesting for me to discover, or decide, is that being a composer means that you can take your influence from anything, and it really doesn’t have to be music.”

While in college at Rice University she went the singer-songwriter route, writing and performing her own songs, rather than training as a classical vocalist. That experience provided a route, albeit a circuitous one, to the theatrical power of her recent works. “Eventually, something about that medium stopped interesting me, in terms of the usual subject matter and then the musical language,” she explained. “But I did miss the sort of direct, confrontational relationship with the audience that you have, and the feeling when you’re performing that you are really addressing the audience and they’re giving something back to you.”

Literature, unsurprisingly, provides much of the stimulation for much of Soper’s work. She is an ingenious collector of texts, as the multivalent sources for “Voices From the Killing Jar” demonstrate, and a deep believer in the idea that “you can use music to explore some things in texts that it’s not really possible to figure out in another way.”

As an example, she mentions “The Crito” (2012), a duo for soprano and percussion based on Plato’s dialogue in which Socrates refuses to consider escaping from prison. One interpretation of the dialogue, she said, is that Socrates “gets so caught up in the rhetoric of his own counterargument that he falls for it. In music you can make a piece where that part of the argument becomes so oppressive or brilliant that you can kind of hear that happen.”

Noah Arjomand

Kate Soper, center, in “Here Be Sirens.”

“Here Be Sirens” contains Soper’s most extensive original writing to date. The piece began life as a play, morphed into an opera, and now exists as a kind of hybrid theater work exploring the roots of the siren myth and whether those creatures can have any kind of actual identity. If that sounds too cerebral to be worthy of the theater, consider that it is “consistently funny — usually droll, occasionally uproarious,” according to the New York Times review of the January premiere.

As for “Helen Enfettered,” its text comes from the Canadian experimental writer Christian Bök’s “Eunoia,” each of whose five chapters uses only one vowel. The fifth chapter tells the story of Helen of Troy, using only words with “e.”

“Something I love is that you don’t really get distracted by the fact that he’s only using one vowel,” she said. “With the two singers I could present this very fractured narrator of Helen, who is pulled in different directions and has all these competing drives within her, and is constantly bouncing between ecstasy and self-loathing.” That is something Soper’s nimble, dynamic music powerfully conveys.

Perhaps the most exciting thing about Soper’s music is the sense that she’s still in the process of discovering that essential voice, and that the process of upheaval, jarring as it can be, is essential to the whole task of being an artist. “It’s your job to constantly change, and to not be afraid of that,” she said. “It’s a luxury to have to indulge in that, rather than trying to settle down and come up with a fixed version of yourself.”